Ancient soft-bodied fossils

1. Even if you don’t have a hard bone, you still have to stay in the stratum

The fossil record in the strata is a "biased census taker" that favors organisms with hard skeletons. However, some soft-bodied organisms have managed to survive and make it into the fossil record, leaving their names in geological history.

△Dinosaur fossils

When it comes to fossils, I believe everyone will naturally think of the tall dinosaur skeletons, strange trilobites, horn-shaped corals, and stone-hard shells displayed in museums.

These are the products of the fossilization process of bones or hard shells of animals in ancient times. The hard parts of animals, such as shells, bones, teeth, etc., are mainly composed of minerals and are more likely to form fossils.

The soft bodies of animals are mostly lost through oxidation, hydrolysis, and enzymatic degradation, and non-mineral biological structures are usually decomposed without a trace, making it difficult to preserve as fossils. To remain in the fossil record, special burial conditions must be met.

The specific environmental conditions under which soft-body fossils of organisms are preserved may vary, but they all have one thing in common: the living organism or the corpse must be buried quickly, isolated from decomposing microorganisms before the soft body decays, and quickly mineralized and recorded in the rock strata.

Insects preserved in amber and mammoths preserved in permafrost are typical examples.

△Ant Amber

Scientists usually compare the Earth's strata to a great book that records the history of the Earth's development, and fossils are the words in this book, recording the organisms and their survival and development conditions in various periods of the Earth's development.

The science that studies fossils is paleontology. The basic purpose and task of paleontology is to study the appearance and development laws of organisms in the history of the earth's development.

After nearly 200 years of research, humans have obtained hundreds of millions of biological hard fossil specimens. Through these specimens, we have gradually shown the overall picture of biological evolution since the Cambrian period.

However, due to the lack of direct fossil evidence, the origin and evolution of many biological categories remain unclear, which is one of the mysteries that humans are working hard to explore.

△Dragonfly fossil

It is estimated that there are more than 1 billion species of organisms that have appeared in the geological period, but humans have only discovered 130,000 species, which is only one ten-thousandth of the species that may have existed in the geological period.

The fossils of these organisms discovered are mostly hard parts of the organisms, while the soft parts with the most information content have disappeared.

Therefore, far-sighted paleontologists have been working hard to find soft-bodied fossils. Although such fossils are rare, they can provide comprehensive and reliable biological information and play a pivotal role in the study of biological taxonomy and systematic evolution.

Soft-bodied fossils can also comprehensively and accurately demonstrate the various symbiotic dependencies, feeding rivalries, and other relationships between organisms and the environment, and between organisms.

Therefore, people call the fossil groups that preserve beautifully soft bodies the treasure house of paleontology. Exploring the fossil reservoir of soft bodies of organisms and conducting in-depth research has become an important hotspot in contemporary paleontology.

△Jellyfish fossil

2. Scientific Observation Window - Fossil Library

The Cambrian Explosion is listed as one of the "six major natural science problems" along with the origin of life and the origin of intelligence. To solve the mystery of the Cambrian Explosion, in addition to theoretical scientific conjectures, it is necessary to discover an appropriate scientific observation window - a fossil repository - to find reliable fossil evidence.

There are dozens of soft-bodied fossil deposits discovered in the world. For paleontologists, the most perfect research object that can decipher the Cambrian explosion and the origin of animal phyla is the Burgess Shale fossil deposit.

01. Burgess Shale Fossil Repository

The Burgess Shale-type fossil deposit was first discovered in 1909 in the Middle Cambrian Burgess Shale in the Canadian Rockies, hence its name.

This fossil deposit has long been a leader in paleontology and evolutionary biology research. Over the past century, more than 50 such fossil deposits have been discovered around the world, but based on the quality of fossil preservation and the diversity of fossil species, only the Burgess Shale Fossil Deposit in Canada and the Chengjiang Fossil Deposit discovered in Yunnan Province, my country in 1984 have become "ideal top research destinations."

△ Location map of the Burgess Shale fossil reservoir and Chengjiang fossil reservoir

02. Chengjiang Animal Fossil Repository

The soft-bodied fossil deposit in Chengjiang, Yunnan, my country, discovered in the 1980s, is the oldest fossil treasure trove in the Phanerozoic Eon and is therefore of the greatest significance, being called one of the major scientific discoveries of the 20th century.

The Chengjiang Fossil Deposit is rich in soft-bodied fossils of various categories, including ancestral types of major coelom categories and representatives of transitional types between categories, providing a wealth of research information for the early explosive evolution of coeloms.

In the more than 30 years since the discovery of the Chengjiang Biota in Yunnan, more than 280 species have been found among hundreds of thousands of fossil specimens. The research results have been published in the three major scientific journals Nature/Science/PNAS 28 times, making it the only fossil site in my country that is a World Natural Heritage.

△Chengjiang Fauna Fuxian Lake Worm

△Chengjiang faunal micronematode fossils

△Reconstruction of the Chinese Microhylids of the Chengjiang Fauna

03. Qingjiang Animal Fossil Repository

Before March 2019, when people talked about fossil groups that proved the existence of the Cambrian Explosion, they would think of the Chengjiang Biota in Yunnan and the Burgess Shale fossil deposit in Canada, but in the future there may be one more: the Qingjiang Biota from Hubei, China.

The characteristics and advantages of the Qingjiang Biota are reflected in five aspects: the highest proportion of new genera and species, the greatest relative diversity of metazoans, the largest number of soft-bodied biological groups, the best fossil morphological fidelity, and the best burial preservation of original organic matter. It has immeasurable research potential.

△Lin Qiaoli fossil of Qingjiang Biota

△New species fossils discovered in the Qingjiang Biota

△Jellyfish fossils found in the Qingjiang Biota

Research on issues such as animal systematics, nutritional dynamics, and the emergence of key evolutionary traits depends on the discovery of more soft-body structures and better morphological preservation, such as internal organs, gill rays, notochord, nervous tissue, cardiovascular system, etc. However, it is well known that these are highly unstable tissues and organs in terms of burial.

The soft-bodied fossils found in the Qingjiang Biota miraculously preserve the original organic matter in the form of native carbonaceous films, which will provide ideal material for taphonomic and geochemical research and further in-depth paleoenvironmental research.

The Qingjiang fossil deposits provide an unparalleled and stunning glimpse into daily life during the Early Cambrian period, all of which has not been "revised" by geological processes.

△ Simulation restoration of Qingjiang biota

The charm of studying soft-bodied fossils lies in the fact that those organisms may have been alive when they were buried. It is a "gathering place of life."

It is this rock unit several meters thick that provides more information about the origin of the modern biosphere, and the task of geological science is to dig out this information and inform humanity.

The fossil deposits of soft-bodied organisms are an important treasure of nature. We must not only carefully protect them, but also increase our efforts to conduct in-depth research on them.

Future little scientists, it’s up to you!

More exciting content can be found in the "Deciphering the Origin of Species Youth Science Series".

Ancient soft-bodied fossils

Deciphering the Origin of Species: A Science Series for Teenagers

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References:

Zhang Xingliang, Shu Degan. Experimental taphonomy and its research progress[J]. Advances in Earth Science, 1998, 13(6):518-525.

Yao Yang. Study on the soft-body fossil-rich layer in the Chengjiang fossil reservoir of the Early Cambrian[D]. Northwest University, 2006.

Wang Yan. Sea anemones in the Chengjiang fossil deposit[D]. Northwest University, 2010.

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Produced by/Jinxiu Science and Creative Team

Written by Shitou Edited by Xia Meixue